1. Field of the Invention
The present invention relates to techniques for mounting a clutch drum to a shaft, where torque must be transferred between the shaft and the clutch drum, and where the shaft has an oil passage supplying oil to actuate the clutch.
2. Description of the Related Art
Clutch drums frequently are mounted to transmission shafts so that an oil passage in the shaft is connected to provide oil to the clutch operating piston. This means that a seal must be formed between the clutch drum and the shaft so that oil does not leak out of the oil passage. Multiple clutch drums (with associated oil passages) often are mounted on a single shaft, making sealing of the various oil passages even more difficult. At the same time, each clutch drum must be mounted to the shaft to allow transmission of torque between the clutch drum and the shaft.
Various techniques have been used in the past to provide a suitable mounting. One technique is to mount the clutch drum on the shaft with a press fit to seal the oil passage. A key then is used to drive the clutch drum. However, keyways are limited in the amount of torque they can carry due to the stresses on the key and the stress concentrations produced in the shaft.
A second approach is to weld the drum to the clutch, or to make both pieces in a single forging. This method is costly and limits the number of clutches on the shaft due to assembly problems.